The major cause of morbidity and mortality in the United States results from coronary and other vascular disease caused by atherosclerosis. Hyperlipoproteinemia has been identified as a significant risk factor for developing these diseases. I propose studying the metabolism of lipoproteins in in vitro cell cultures derived from normal individuals. The synthesis and catabolism of lipoproteins will be studied in cell culture and the metabolic effects of lipoproteins on cells in culture will be investigated. In vitro study also allows an investigation of the relative contributions of the lipid and the protein moieties to the maintenance of cells in culture. This information will be used to better understand normal plasma lipid and lipoprotein metabolism and to explore the genetic and metabolic defects in the hyperlipoproteinemias and hypolipoproteinemias.